Is there a way for my to use serial port on a guest linux OS?
You can use a RAW
parameter in the template or set it as default. You have an example on how to add a serial console in the documentation:
RAW = [ type = "kvm",
data = "<devices><serial type=\"pty\"><source path=\"/dev/pts/5\"/><target port=\"0\"/></serial><console type=\"pty\" tty=\"/dev/pts/5\"><source path=\"/dev/pts/5\"/><target port=\"0\"/></console></devices>" ]
For more information check libvirt documentation page.
Thank You!!